Electrical switches using push button or plunger type switch actuators have many applications including use in automobile car doors, ignition circuits, power take-offs for lawn mowers and garden tractors, refrigerator doors, home appliances, and the like. These push buttons may be normally open, normally closed or a combination of the two.
It is possible to construct switches having more than two terminals, which combine the features of normally open and normally closed switches. For example, a “double-pole double-throw” switch behaves as a normally open switch and a normally closed switch in parallel operated by a single plunger. When the plunger is in a normal position, a pair of normally closed terminals is bridged and a pair of normally open terminals is isolated. Alternatively, when the plunger is moved to an actuated position, the normally open terminals are bridged and the normally closed terminals are isolated. A “single-pole double-throw” switch behaves like a double-pole double-throw switch in which one of the normally open terminals is coupled to one of the normally closed terminals. When the plunger is in the normal position, a common terminal is bridged with a normally closed terminal while a normally open terminal is isolated. Alternatively, when the plunger is in the actuated position, the common terminal is bridged with the normally open terminal while the normally closed terminal is isolated. Such switches can then be configured to communicate on a LIN or CAN bus.
Typically located within a housing supporting electrical switch are electrical components such as contacts, printed circuit boards, etc. that are adverse to contamination, such as water or debris. It is not uncommon for such electrical switches to be exposed to such harsh environments, especially those switches used on garden tractors.
Further discussion relating to the different switch constructions can be found in U.S. Pat. No. 5,528,007 entitled PLUNGER SWITCH AND METHOD OF MANUFACTURE that issued on Jun. 18, 1996 and assigned to the assignee of the present disclosure. U.S. Pat. No. 5,528,007 is incorporated herein by reference in its entirety.